Myocardial infarction (MI) is a major cause of cardiac-related death in the US and those fortunate to survive the acute event suffer from chronic risk of arrhythmia, stroke and congestive heart failure. Repairing the heart is difficult because cardiomyocytes are post-mitotic and cannot proliferate in order to regenerate damaged tissue. Recent work has demonstrated that human cardiomyocytes can be derived from embryonic stem (ES) and induced pluripotent stem (iPS) cells, as well as transdifferentiated from other cells. However, survival and functional integration of these cardiomyocytes into stereotypical vascularized myocardium is still a major and unresolved challenge. This proposal describes a breakthrough towards therapeutic cell delivery by wrapping each cell in a nanostructured extracellular matrix (ECM) scaffold tailor made for enhancing survival, myogenesis and integration into infarcted myocardium. The key innovation in our approach is the ability to engineer 50-100 nm thick sheets of ECM with defined protein composition and shape and wrap this around individual cells or small cell ensembles. This is an improvement over current encapsulation technology because we can build the ECM around cardiomyocytes and endothelial cells to mimic the ECM that naturally surrounds these cells in the healthy heart. This is critical, because the ECM is a primary regulator of integrin binding, growth factor sequestration and mechanotransduction. Our preliminary results demonstrate that our novel surface-initiated assembly technique can build an ECM nano-scaffold from a range of matrix proteins and shrink wrap cardiomyocytes and endothelials cells. Further, we have shown using corneal endothelial cells that we can effectively delivery cells in vivo. This proposal will build upon these results by achieving three primary aims. One, develop the ECM nano-scaffold technology to shrink wrap cardiomyocytes and endothelial cells in engineered layers of fibronectin, laminin and collagen type IV that match the matrix in the native myocardium. Two, interrogate the role of ECM nano-scaffold composition, size and cell population on maximizing muscle formation, pre-vascularization and contractility in 3D tissue. Looking forward, achieving these aims will result in an injectable cell delivery technology that has enhanced capability to promote the retention, survival, integration, myogenesis and vascularization of cardiomyocytes and endothelial cells into the injured heart. This would have profound consequences by leading towards clinically-relevant therapeutic strategies to decrease morbidity and mortality in MI and cardiovascular disease patients